There are some issues with using ubuntu as server distro, including hardware certification and tech support. Enterprise distros may seem boring but they go through hell lot more QAs and certifications and take bugs found on supported hardware pretty seriously.

I've seen quite some headaches people were having with ubuntu with completely generic dell servers certified for RHEL and SLES. Their solution? Just try installing different versions of ubuntu and use whatever which doesn't crash. It almost felt surreal. :-(